The enemy I must fight is—still in this city. The boy chose his conviction. And to protect the girl. Masters and Servants battle for the wish-granting Holy Grail—the "Holy Grail War." The war that began in Fuyuki City after ten years becomes distorted, twisted, and warped due to the participation of Zouken Matou, head of the Matou family, one of the three founding families of the Holy Grail War. Zouken summons True Assassin as his Servant. A shadow of unknown origin writhes through the town, and Masters and Servants fall one after another. Shirou Emiya, who had joined the war as a Master, is also wounded and loses his Servant, Saber. Yet, to protect Sakura Matou, Shirou refuses to withdraw from the battle. Though Sakura worries for Shirou’s safety, she too becomes ensnared by the fate of a magus... "I promise. I will—" He vowed never to betray her—her alone. The earnest wishes of the boy and girl are swallowed by the dark shadow.